• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1901-1910
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• 2023

The safety-class (1E) digital control system (DCS) of nuclear power plant characterized structural multiple redundancies, therefore, it is important to quantitatively evaluate the reliability of DCS in different degree of backup loss. In this paper, a reliability evaluation model based on T-S fuzzy fault tree (FT) is proposed for 1E DCS of nuclear power plant, in which the connection relationship between components is described by T-S fuzzy gates. Specifically, an output rejection control system is chosen as an example, based on the T-S fuzzy FT model, the key indicators such as probabilistic importance are calculated, and for a further discussion, the T-S fuzzy FT model is transformed into Bayesian Network(BN) equivalently, and the fault diagnosis based on probabilistic analysis is accomplished. Combined with the analysis of actual objects, the effectiveness of proposed method is proved.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.638-641
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• 2004

Returned laser pulse has certain relationship with vegetation canopy structure (canopy closure, height, LAI, biomass). This study attempts to analyze the characteristics of airborne laser scanner data over very dense forest canopy. Discrete pulse laser scanner data were obtained on April 25, 2004 along with digital aerial color imagery. Using forest stand maps, 14 sample stands of 7 species groups were selected and the elevations from the first and last laser return were compared. From the preliminary analysis, we found that the difference between the first and last return was higher with deciduous forest stand than in coniferous stand. Although difference between the first and the last laser returns often corresponds to tree height, it would not be the case for the forest site having very dense canopy structure.

• Nuclear Engineering and Technology
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• v.44 no.4
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• pp.405-414
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• 2012

In this paper, we propose a reliability estimation method for DI&C systems. At the system level, a fault tree model is suggested and Boolean algebra is used to obtain the minimal cut sets. At the component level, an exponential distribution is used to model hardware failures, and Bayesian estimation is suggested to estimate the failure rate. Additionally, a binomial distribution is used to model software failures, and a recently developed software reliability estimation method is suggested to estimate the software failure rate. The overall system reliability is then estimated based on minimal cut sets, hardware failure rates and software failure rates.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.287-289
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• 2000

처리시간 지연에 민감한 패킷 플로우, 비디오, 오디오 스트림과 같은 어플리케이션을 보안성이 없는 인터넷상에서 멀티캐스팅할 때에 데이터의 기밀성, 메시지 또는 발신자 인증, 무결성 그리고 부인 방지 등의 보안 서비스를 제공하기 위해서는 여러 가지 암호 및 인증 기법이 필요하다. 본 논문에서는 이러한 멀티캐스트 스트림과 플로우에 대한 서명/인증 기법의 특성과 요구사항을 분석해 보고 기존에 제시된 each-sign 기법, one-time 서명 기법, star-chaining 기법, 그리고 Tree-chaining 기법에 대한 상호 비교 및 분석을 통해 이들의 서명/검증 계산시간과 통신 트래픽 오버헤드에 대한 단점을 효율적으로 개선하여 Enhanced Tree-chaining 기법을 제안한다. 서명 및 검증 시간은 약 50% 단축되며 통신 오버헤드는 log2n배 축소되는 향상을 기대할 수 있다. 또한 인증 소요 시간에 주요 요인이 되는 것은 서명/검증의 계산시간이 아니라 chaining 오버헤드의 크기임을 유추해 낸다.

• International Journal of CAD/CAM
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• v.8 no.1
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• pp.37-40
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• 2009

Based on the study of Digital Elevation Simplification Model and fractal theory, this paper put forward a new method to simulate complex terrain. That use simplified DEM data to construct terrain frame based on the quad tree at first, and then use fractal to generate the details of every node of the tree. In the process of construction, the LOD theory is used to simplify the terrain and get its typical data. According to the change of view position and direction, the paper gives a new way to judge the visibility of the surface patch. Experimental results show that this algorithm is simple, efficient and supports the real time dynamic simulation of terrain model.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.06a
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• pp.255-256
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• 2018

본 논문에서는 비디오 부호화 성능 향상을 위하여 QTBT (QuadTree Plus Binary Tree) 블록 구조에서 대각선 움직임 분할 (DMP: Diagonal Motion Partition) 방법을 제안한다. HEVC 이후의 비디오 압축 표준을 위한 탐색 과정에서 다양한 부호화 성능 향상 방법들이 제안되고 있으며, 그 중 제안하는 대각선 움직임 분할 방법은 하나의 정방형 혹은 직방형의 부호화 유닛 (CU: Coding Unit)을 두 개의 삼각형으로 분할하여 움직임 예측 및 보상을 수행하는 방법이다. 제안하는 방법에서는 두 가지 대각선 방향만을 사용하여 블록을 분할하지만, QTBT 블록 구조와 결합하여 다양한 임의의 블록 분할 형태를 표현하는 것이 가능하다. 본 논문에서는 제안하는 방법을 JEM-7.0에 구현하여 0.15%의 부호화 효율 향상 결과를 획득하였다.

• Journal of applied mathematics & informatics
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• v.40 no.5_6
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• pp.883-896
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• 2022

A hereditary base-b representation, used in the celebrated Goodstein's theorem, can easily be converted into a labeled rooted tree. In this way it is possible to give a more elementary geometric proof of the aforementioned theorem and to establish a more general version, geometrically proved. This view is very useful for better understanding the underlying logical problems and the need to use transfinite induction in the proof. Similar problems will then be considered, such as the so-called "hydra game".

• Journal of Korean Society for Geospatial Information Science
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• v.24 no.4
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• pp.67-74
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• 2016

Drone images with high spatial resolution are emerging as an alternative to previous studies with extraction limits in high density forests. Individual tree in the dense forests were extracted from drone images. To detect the individual tree extracted through the image segmentation process, the image segmentation results were compared between the combination of DSM and all R,G,B band and the combination of DSM and R,G,B band separately. The changes in the tree density of a deciduous forest was experimented by time and image. Especially the image of May when the forests are dense, among the images of March, April, May, the individual tree extraction rate based on the trees surveyed on the site was 50%. The analysis results of the width of crown showed that the RMSE was less than 1.5m, which was the best result. For extraction of the experimental area, the two sizes of medium and small trees were extracted, and the extraction accuracy of the small trees was higher. The forest tree volume and forest biomass could be estimated if the tree height is extracted based on the above data and the DBH(diameter at breast height) is estimated using the relational expression between crown width and DBH.

• Journal of Digital Convergence
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• v.12 no.1
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• pp.415-421
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• 2014

In this paper, we proposed problem and improvement of halftoning using random space filling curve. Random space filling curve is developed as a solution for shortcoming which space filling curve has self-similarity. It is used to reduce regular pattern can be occurred in constant brightness area in order that randomness apply to scanning path. But there is a problem that some area along scanning path can show too bright result in halftoning using random space filling curve. In this paper, we analyzed cause of problem and proposed single pixel error diffusion as a solution method. This method can avoid over-accumulated error and show better result in halftoning.

• Journal of Digital Contents Society
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• v.7 no.1
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• pp.53-58
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• 2006

In this paper, We proposed extraction method using EZW a specific character and then add watermark significant coefficient of image. After wavelet transform in image, the significant coefficient value add to watermark information image. In this method, the locations of nonzero wavelet coefficients are encoded with a tree structure, called zerotree, which can exploit the self-similarity of the pyramid decomposition across different scales. The simulation shows that this method provides a superior performance over conventional method and can be successfully applied to the application areas that requires of progressive transmission and search for image data.